The present application relates to a semiconductor structure, and particularly to high electron mobility transistors (HEMT's) including self-aligned embedded elemental semiconductor contact structures and methods of manufacturing the same.
Most metallization schemes for high electron mobility transistors require a high annealing temperature above 900° C. to form low resistance Ohmic contact to a compound semiconductor material such as AlGaN. However, the integrity of a gate electrode for a high electron mobility transistor is compromised above 600° C. due to the reaction with aluminum in an Ohmic metallization scheme. Reducing the temperature of the metallization process as known in the art always results in formation of inferior quality contacts. Further, the quality of contacts to the compound semiconductor material layer is highly variable due to process variations and temperature dependence of the metallization process.